[Very rough draft - I really think the matter deserves a complete analysis - which I am not qualified to write]
In my study of Halachic literature, I have often noticed that there are two different schools of thought among posekim.
Among some Posekim, there is an attitude of "יקוב הדין את ההר". The posek analyses the sources and rules based on his own understanding of them. Even if his predecessors ruled differently or understood the sources differently - אין לו לדיין אלא מה שעיניו רואות and הלכה כבתראי as explained by the Rema  (CM 25). This school considers the autonomy of the Posek to be central whereas precedent is only important insofar as it helps the Posek clarify the sources but carries no weight on its own.
At the opposite extreme, lies those posekim who feel it necessary to cite and discuss every possible precedent on the issue. These will rarely dismiss the earlier poskim based on their own reading of the sources but instead will insist that one must try to follow all opinions. According to this school, the fact that an eminent authority cites an opinion is itself of Halachic weight (perhaps of even greater Halachic weight then his own reading of the sources) and the autonomy of the Posek is limited.
There are of course a variety of positions between the two extremes. I believe it might be instructive before examining any posek to first identify to which school of pesak he belongs to analyse his pesak accordingly.
 The best example of this school of thought is R' Yaakov Emden who was fiercly independant in his pesakim (See for example this post in which the Yaavetz cites his father that - "Any dayan who is not willing to erase a seif in SA is not worthy of ruling. Mor U' Ketziah is simply full of examples in which the Yaavetz does just that.), then one might point to the Rogatchover who felt himself obligated to the Rambam only (note his correspondence with the SE that Marc Shapiro discusses in his book), and the final and most influential authority in this group is the Aruch Ha-Shulkhan who similarly is not afraid to argue against any of his predecessors if his own reading of the sources leads to a different ruling (See for example his ruling concerning one who skips p'sukei d'zimra if he need complete it after davening). R' Moshe Sternbuch in his Teshuvot V' Hanhagot is also roughly part of this group as he rarely cites Acahronim (but see his Hakdamah) but has his own highly original method of Pesak (see Tradition, R' Moshe Sternbuch's Halachic Novellae).
 Y. Ta Shema has an article on the principle of Halacha K'Basrai that is somewhat relevant here.
 The most important posek from this school of thought is the Mishna Berurah who cites every Acharon possible and considers them all obligatory (to some degree at least - cf. B. Brown's article in Contemporary Halacha on Soft-Stringency in the Mishna Berurah). A comparison - seif by seif of the Mishna Berurah and the Arukh HaShulkhan's stance to various issues would be most instructive (the new AS's with the MB on the bottom can give you some idea of the differences between them).
I do not know if Chacham Ovadiah belongs in this category. True he is careful to cite alll the Acharonim on any issue but I don't know to what extent he considers them obligatory. Perhaps he is simply trying to gather all the arguments relating to the subject together. The same applies to R' Yosef Zechariah Stern. (Benny Brown's article on "Hachmarah" should also be relevant.)